The present invention relates to a novel therapeutic composition that contains halogenated bi-cyclic structures for treatment of constipation and use thereof.
Prostaglandins (hereinafter referred to as PGs) is the name of the group of fatty acids which possess various physiological activities and contained in human and animal tissues and organs. PGs basically contain the prostanoic acid skeleton of the following formula: 
and some synthetic products may contain the above skeleton with some modification. PGs are classified into several types according to the structure and substituents on the five-membered ring, for example, 
and the like. Further, they are classified into PG1s containing a 13,14-double bond; PG2s containing, 5,6- and 13,14-double bonds; and PG3s containing 5,6-, 13, 14- and 17,18-double bonds.
PGs are expressed as follows. In PGs, the carbons constituting an xcex1-chain, an xcfx89-chain and a five-membered ring are numbered according to the basic skeleton as follows: 
That is, in the basic skeleton, the constituent carbon atoms are numbered in such a way that the carbon atom in the carboxyl group is C-1, and the xcex1-chain contains C-2-C-7, the number increasing toward the ring, the five-membered ring contains C-8-C-12, and the o-chain contains C-13-C-20. When the carbons of xcex1-chain are fewer, the numbers of the carbon atoms ensuing C-2 should be properly shifted, and when more than 7, the compound is named provided that carbon at the C-2 position has substituent instead of carboxyl group (at the C-1 position). When the xcfx89-chain contains fewer carbon atoms they should be numbered correspondingly smaller than 20, and when more than 8, the carbon atoms at the 21 position and thereafter should be regarded as a substituent. As configuration, it is considered according to that of the above essential skeleton unless otherwise described.
For example, PGD, PGE and PGF mean compounds having hydroxyl group at the C-9 and/or C-11 positions. In the present invention, PGs also include those having other group instead of the hydroxyl group on the C-9 and/or C-11 positions, they being named as 9-dehydroxy-9-substituted or 11-dehydroxy-11-substituted compounds.
In addition, PGs may include the isomers, such as bi-cyclic tautomers, optical isomers; geometrical isomers, or the like.
PGs are known to have various pharmacological and physiological activities, for example, vasodilation, inducing of inflammation, platelet aggregation, stimulating uterine muscle, stimulating intestinal muscle, anti-ulcer effect and the like. PGEs or PGFs are found to possess contraction of intestines caused by intestinal stimulation is great, while enteropooling effect is poor.
Accordingly, it is impossible to use PGEs or PGFs as cathartics because of side effects such as stomachache caused by the intestinal contraction.
On the other hand, PGs having a 13,14-single bond and a C-15 constituting carbonyl group, and those having a 13,14-double bond and a C-15 constituting carbonyl group are found to exist in human or animal metabolites. These 13,14-dihydro-15-keto-prostaglandins and 15-keto-prostaglandins (hereinafter referred to as 15-keto-PGs) are known to be naturally produced metabolites by enzymatic metabolism of the corresponding PGs in vivo. These 15-keto-PGs have been reported to hardly exhibit various physiological activities that PGs possess and be pharmacologically and physiologically inactive metabolites [see, Acta Physiologica Scandinavica, 66, p.509-(1966)].
U.S. Pat. No. 5,317032 to Ueno et al. describes prostaglandin cathartics, including the existence of bi-cyclic tautomers. However, the pronounced activity as anti-constipation treatment and prevention agents of the bi-cyclic tautomers has not been heretofore known.
While estimating the pharmacological activities of the analogues of 15-keto-PGs, however, the present inventors have found that the corresponding bi-cyclic compounds, i.e., the bi-cyclic tautomers, substituted by one or more halogen atoms can be employed in small doses for relieving constipation. At the C-16 position, especially, fluorine atoms, can be employed in small doses for relieving constipation. Where desired, larger doses to cause strong cathartic effect can be employed, although the primary purpose of the present invention is to restore a normal number of bowel movements (3 to 7 per week).
An object of the present invention is to provide a composition for treatment of constipation comprising bi-cyclic-halogenated compounds without substantive side effects such as stomachache caused by intestinal contraction. Accordingly, the bi-cyclic-halogenated compounds of the present invention may be used not only for treatment of chronic or intermittent constipation, but also for treatment or prevention of constipation (as well as to effect loose bowels when desired) in the patients suffering from constipation associated with, for example, in hernia or cardiovascular system disease, in order not to strain at stool, or suffering from proctogenic diseases. Moreover, they may be used to produce normal bowel movements for washing out harmful substances from intestine in case of drug or food poisoning. Additionally, the bi-cyclic halogenated compounds may be used as a bowel cleansing agent used for preparation of the bowel prior to preventative, diagnostic or surgical procedures.
The present invention provides an anti-constipation composition (prevention and/or treatment of constipation)containing bi-cyclic-halogenated compounds as active ingredients.
Cathartics work by the combination of one or more of the four mechanisms shown below, thereby increasing water content of feces and promoting transfer of the content in the intestines:
(i) Water and electrolytes may be kept in intestines owing to the hydrophilicity or osmotic pressure of the drug, thereby the intraintestinal content increased in volume which indirectly results in faster transfer thereof.
(ii) The drug may work on the intestinal mucosa to reduce total amount of normal absorption of electrolytes and water and increase the amount of water, indirectly resulting in faster transfer of the intraintestinal content.
(iii) The drug may work on the intestinal mucosa to increase total amount of normal secretion of electrolytes and water and increase the amount of water, directly and/or indirectly resulting in faster transfer of the intraintestinal content.
(iv) The drug firstly works on intestinal movement to fasten transfer, indirectly resulting in reduced net absorption of water and electrolytes because the time for them to be absorbed is reduced.
The enteropooling test employed in the present invention is intended to investigate mainly on the action (ii) and/or (iii), which assesses the effect of the drug on the intraintestinal water pool by measuring the volume of the intraintestinal content. The bi-cyclic-halogenated compounds of the present invention may show extremely great enteropooling effect. However, they hardly or slightly cause contraction of intestines which is one of indexes for assessment of the action (iv). Accordingly, the bi-cyclic-halogenated compounds of the present invention are considered to alleviate constipation by mainly acting on intestinal mucosa directly or indirectly to affect transfer of electrolytes and water from intestinal walls into blood vessels and/or from blood vessels into intestines, resulting in reduced water absorption and/or in increased water secretion through the intestines, increased intraintestinal water pool and promoted transfer of the intraintestinal content.
A preferred compound used in the present invention is represented by formula (I): 
where V1 and V2 are carbon or oxygen atoms;
W1 and W2 are 
R3 and R4 are both hydrogen atoms or one of them is OH;
X1 and X2 are hydrogen, lower alkyl or halogen atom, and at least one of these is a halogen atom;
Z is a carbon, oxygen, sulfur or nitrogen atom;
R2 is a hydrogen atom or lower alkyl;
Y is a saturated or unsaturated C2-10 hydrocarbon chain which is unsubstituted or substituted by oxo, halogen, an alkyl group, hydroxyl or aryl;
A is xe2x80x94CH2OH, xe2x80x94COCH2OH, xe2x80x94COOH or its functional derivative; and
R1 is a saturated or unsaturated, lower hydrocarbon forming a straight-chain, a branched-chain or a ring, which is unsubstituted or substituted by halogen, oxo, hydroxy, lower alkoxy, lower alkanoyloxy, lower cycloalkyl, lower cycloalkyloxy, aryl, or aryloxy. Preferably R1 is not substituted. Where a substituent is present, care must be exercised to avoid possible steric hinderance in formation of the bi-cyclic compound from or in association with the corresponding mono-cyclic PGs.
The steric configuration of C-15 can be R, S, or a mixture thereof.
The bond between C-13 and C-14 position can be a single or double bond.
In the above formula, the term xe2x80x9cunsaturatedxe2x80x9d is intended to include at least one or more double bonds and/or triple bonds that are isolatedly, separately, or serially present between the carbon atoms of the main and/or side chains. An unsaturated bond between two serial positions is represented by denoting the lower number of the two positions, and an unsaturated bond between two distal positions is represented by denoting both of the positions. Preferred unsaturated bonds are a double at position 2 and a double or triple bond at position 5.
The term xe2x80x9clowerxe2x80x9d is intended to include a group having 1 to 8 carbon atoms, unless otherwise specified.
The term xe2x80x9cringxe2x80x9d includes lower cycloalkyl, lower cycloalkoxy, aryl or aryloxy.
The term xe2x80x9chalogenxe2x80x9d includes fluorine, chlorine, bromine, or iodine atom. Particularly preferable is a fluorine atom.
The term xe2x80x9clower alkoxyxe2x80x9d refers to a group of lower alkyl-Oxe2x80x94, wherein lower alkyl is a straight or branched chain saturated hydrocarbon group containing 1 to 6 carbon atoms and includes, for example, methyl, ethyl, propyl, isopropyl, buyl, isobutyl, t-butyl, pentyl and hexyl.
The term xe2x80x9chydroxy(lower)allylxe2x80x9d refers to a lower alkyl as defined above which is substituted with at least one hydroxy group such as hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl and 1-methyl-1-hydroxyethyl.
The term xe2x80x9clower alkanoyloxyxe2x80x9d refers to a group represented by the formula RCOxe2x80x94Oxe2x80x94, wherein RCOxe2x80x94 is an acyl group formed by oxidation of a lower alkyl group as defined above, such as acetyl.
The term xe2x80x9clower cycloalkylxe2x80x9d refers to a cyclic group formed by cyclization of a lower alkyl group as defined above but contains three or more carbon atoms, and includes, for example, cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.
The term xe2x80x9clower cycloalkyloxyxe2x80x9d refers to the group of lower-cycloalkyl-Oxe2x80x94, wherein lower cycloalkyl is as defined above.
The term xe2x80x9carylxe2x80x9d may include unsubstituted or substituted aromatic carbocyclic or heterocyclic groups (preferably mono-cyclic groups), for example, phenyl, naphthyl, tolyl, xylyl, furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, furzanyl, pyranyl, pyridyl, pyridazyl, pyrimidryl, pyrazyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, piperidino, piperazinyl, morpholono, indolyl, benzothienyl, quinolyl, isoquinolyl, puryl, quinazolinyl, carbazolyl, acridinyl, phenathridinyl, benzimidazolyl, benzimidazolonyl, benzothiazolyl and phenothiazinyl. Examples of substituents are halogen atom and halo(lower)alkyl, wherein halogen atom and lower alkyl are as defined above.
The term xe2x80x9caryloxyxe2x80x9d refers to a group represented by the formula Arxe2x80x94O, wherein Ar is aryl as defined above.
The bi-cyclic-16-halogen compounds used in the present invention may be salts or those with an esterified carboxyl group or etherified group. Such salts include pharmaceutically acceptable salts, for example, those of alkali metals such as sodium, potassium; those of alkaline earth metals such as calcium, magnesium; those of physiologically acceptable ammonium salts such as ammonia, methylamine, dimethylamine, cyclopentylamine, cyclohexylamine, benzylamine, piperidine, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, monomethylmonoethanolamine, trometamine, lysine, procaine, caffeine, arginine, tetralkylammonium salt and the like. These salts may be prepared by a conventional process, for example, from the corresponding acid and base or by salt interchange.
Such esters and ethers include, for example, straight or branched alkyl esters and ethers which may contain one or more unsaturated bonds such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, t-butyl, pentyl, 2-ethylhexyl; those having an alicyclic group such as a cyclopropyl, cyclopentyl or cyclohexyl group; those containing an aromatic group such as a benzyl or phenyl group (wherein the aromatic group may contain one or more substituents); a lower alkenyl such as ethynyl and propynyl, hydroxyalkyl or alkoxyalkyl such as hydroxyethyl, hydroxyisopropyl, polyhydroxyethyl, polyhydroxyisopropyl, methoxyethyl, ethoxyethyl or methoxyisopropyl ester or ether; optionally substituted aryls such as phenyl, tosyl, t-butylphenyl, salicyl, 3,4-di-methoxyphenyl and benzamidophenyl; alkylsilyls such as a trimethylsilyl or triethylsilyl; or a tetrahydropyranyl ester or ether.
Preferred esters and ethers include, for example, straight-chain or branched lower alkyl such as methyl, ethyl, propyl, n-butyl, isopropyl or t-butyl; a benzyl; or hydroxyalkyl such as a hydroxyethyl or hydroxyisopropyl.
Preferred A is xe2x80x94COOH or its pharmaceutically acceptable salt or ester.
Preferred X1 and X2 are both being halogen atoms, and more preferably, fluorine atoms.
Preferred W1 is xe2x95x90O.
Preferred W2 is where R3 and R4 are both hydrogen atoms.
Preferred Z is an oxygen atom.
Preferred Y is an unsubstituted saturated or unsaturated hydrocarbon chain having 6-8 carbon atoms.
Preferred R1 is an unsubstituted saturated or unsaturated hydrocarbon chain having 4-8 carbon atoms.
R2 is preferably a hydrogen atom.
The composition of the present invention may include the isomers of the above compounds. Examples of such isomers include mono-cyclic tautomers having a keto group at the C-15 position and halogen at the C-16 position; optical isomers; geometrical isomers and the like. 
The tautomerism between the oxygen atom at the C-11 position and the keto group at the C-15 position, shown above, is especially significant in the case of compounds having a 13,14-single bond and two fluorine atoms at the C-16 position.
It has been discovered that in the absence of water, compounds represented by Formula (I) exist predominantly in the form of the bi-cyclic compound. In aqueous media, it is believed that hydrogen bonding occurs between, for example, the ketone position at the C-15 position, thereby hindering bi-cyclic ring formation. In addition, it is believed that the halogen atom(s) at the C-16 position promote bi-cyclic ring formation. The mono-cyclic/bi-cyclic structures, for example, may be present in a ratio of 1:6 in D2O; 1:10 in CD3OD-D2 O and 4:96 in CDCl3. Accordingly, a preferable embodiment of the present invention is the composition in which the bi-cyclic form is present in ratio of bi-cyclic/mono-cyclic of least 1:1, and preferably 20:1, or even greater to substantially all bi-cyclic compound; 100% bi-cyclic compound is within this invention.
The above described bi-cyclic-16-halogen compound may prepared according to the general process set forth below:

To a mixture of pyridine (0.77 g) and isopropyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-(3,3-ethylenedioxydecyl)cyclopentyl]hept-5-enoate (1) (4.05 g) in dichloromethane, a solution of tosyl chloride (1.86 g) in dichloromethane was added at 0xc2x0 C., and stirred for 2 days at the temperature. During the reaction, each tosyl chloride (5.58 g) and pyridine (2.31 g) was added in three portions. After the usual work-up, the crude product was chromatographed on silica gel to give isopropyl (Z)-7-[(1R,2R,3R,5S)-2-(3,3-ethylenedioxydecyl)-S-hydroxy-3-(p-toluenesulfoxy)cyclopentyl]hept-5-enoate (2). Yield 3.45 g, 64.1%.
2. Preparation of Isopropyl (Z)-7-[(1R,2S)-2-(3,3-ethylenedioxydecyl)-5-oxocyclopent-3-enyl]hept-5-enoate (3) 
Isopropyl (Z)-[1R,2R,3R,5S)-2-(3,3-ethylenedioxydecyl)-5-hydroxy-3-(p-toluenesulfoxy)cyclopentyl]hept-5-enoate (2) (1.72 g) was oxidized in acetone at xe2x88x9240xc2x0 C. to xe2x88x9220xc2x0 C. with Jones reagent for 4 hours. After the usual work-up, the crude product was passed through silica gel pad with n-hexane/ethyl acetate (3.5/1). The product was further chromatographed on silica gel (n-hexane/ethyl acetate=4/1). Isopropyl (Z)-7-[(1R,2S)-2-(3,3-ethylenedioxydecyl)-5-oxo-cyclopent-3-enyl]hept-5-enoate (3) was obtained. Yield 0.81 g, 64.6%.
3. Preparation of Isopropyl-7-[(1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-3-hydroxymethyl-5-oxocyclopentyl]hept-5-enoate (4) 
Isopropyl (Z)-7-[(1R,2S)-2-(3,3-ethylenedioxydecyl)-5-oxo-cyclopent-3-enyl]hept-5-enoate (3) (0.81 g) and benzophenone were dissolved in methanol. Under argon atmosphere, the solution was irradiated with 300-W high-pressure mercury lamp for 4 hours and 40 minutes. After evaporation of the solvent, the crude product was chromatographed on silica gel (n-hexane/ethyl acetate=3/2) to give isopropyl-7-[(1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-3-hydroxymethyl-5-oxocyclopentyl]hept-5-enoate (4). Yield 0.41 g, 47%.
4. Preparation of Isopropyl-7-[1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-5-oxo-3-(p -toluenesulfoxymethyl)cyclopentyl]hept-5-enoate (5) (4) (5) 
Isopropyl-(1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-3-hydroxymethyl-5-oxocyclopentyl]hept-5-enoate (4) (0.21 g) and pyridine (0.07 g) were dissolved in dichloromethane. To this solution, tosyl chloride (0.17 g) was added at 0xc2x0 C., and the mixture was stirred for 72 hours. After the usual work-up, the crude product was chromatographed on silica gel to give isopropyl 7-(1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-5-oxo-3-(p-toluenesulfoxy)methylcyclopentyl]hept-5-enoate (5). Yield 0.25 g, 89%.
5. Preparation of Isopropyl-7-[(1R,2R,3R)-2-(3,3-ethylenedioxydecyl)-3-iodemethyl-5-oxocyclopentyl]hept-5-enoate (6) 
Isopropyl 7-(1R,2S,3R)-2-(3,3-ethylenedioxydecyl)-5-oxo-3-(p-toluenesulfoxy)methylcyclopentyl]hept-5-enoate (5) (0.25 g) was dissolved in acetone, and sodium iodide (0.12 g) was added. The mixture was refluxed for 3 hours. Sodium iodide (0.097 g) was added to the mixture, and the mixture was refluxed for additional 80 minutes. After the usual work-up, the crude product was chromatographed on silica gel (n-hexane/ethyl acetate=5/1) to give isopropyl 7-(1R,2R,3R)-2-(3,3-ethylenedioxydecyl)-3-iodemethyl-5-oxocyclopentyl]hept-5-enoate (6). Yield 0.16 g, 68%.
6. Preparation of Isopropyl 7-(1R,2R,3R)-3-iodemethyl-5-oxo-2-(3-oxodecyl)cyclopentyl]hept-5-enoate (7) 
Isopropyl 7-(1R,2R,3R)-2-(3,3-ethylenedioxydecyl)-3-iodemethyl-5-oxocyclopentyl]hept-5-enoate (6) (0.16 g) was dissolved in a mixed solvent of acetic acid/water/tetrahydrofuran (3/1/1). The mixture was stirred for 20 hours at room temperature and for 2.5 hours at 50xc2x0 C. After evaporation of the solvent, the obtained residue was chromatographed on silica gel (n-hexane/ethyl acetate =1/1) to give isopropyl 7-(1R,2R,3R)-3-iodemethyl-5-oxo-2-(3-oxodecyl)cyclopentyl]hept-5-enoate (7). Yield. 0.13 g; 86%.
7. Preparation of Isopropyl 7-(1S,3S,6S,7R)-3-heptyl-3-hydroxy-bicyclo[4.3.0]nonane-8-one-7-yl]hept-5-enoate (8a) and Isopropyl 7-(1S, 3R, 6S, 7R)-3-heptyl-3-hydroxy-bicyclo[4.3.0]nonane-8-one-7-yl]hept-5-enoate (8b) 
Isopropyl 7-(1R,2R,3R)-3-iodemethyl-2-(3-oxodecyl)-5-oxocyclopentyl]hept-5-enoate (7) (0.0574 g) and zirconocene dichloride were dissolved in tetrahydrofuran. The mixture was sonicated under argon stream to purge the air out from the mixture. To the mixture samarium iodide in tetrahydrofuran (0.1 M, 2.1 mL) was added dropwise. The mixture was stirred for 30 minutes at room temperature, and then hydrochloric acid (0.1M, 1 mL) was added. After the usual work-up, the crude product was chromatographed on silica gel (n-hexane/ethyl acetate=5/1). Two bicyclic products, more polar (8a) and its epimer, less polar (8b) and starting material (7) were obtained as follows:
Isopropyl 7-(1S,3S,6S,7R)-3-heptyl-3-hydroxy-bicyclo[4.3.0]nonane-8-one-7-yl]hept-5-enoate (8a) and Isopropyl 7-(1S,3R,6S,7R)-3-heptyl-3-hydroxy-bicyclo[4.3.0]nonane-8-one-7-yl]hept-5-enoate (8b): Yield 8(a) 5.1 mg, Yield 8(b) 7.2 mg, Recovery of starting material (7) 26.7 mg.
A theoretical synthesis for a compound represented by Formula (I) where Z is a sulfur atom and W1 is an xe2x80x94OH group is set forth below: 
A theoretical synthesis for a compound represented by Formula (I) where Z is a sulfur atom and W1 is a keto is set forth below: 
A theoretical synthesis for a compound represented by Formula (I) where Z is a sulfur atom, W1 is a keto and X1 and X2 are fluorine atoms is set forth below: 
A theoretical synthesis for a compound represented by Formula (I) where Z is a nitrogen atom is set forth below: 
Another theoretical synthesis of a compound represented by Formula (I) where Z is a nitrogen atom is set forth below: 
The preparations in the present invention are not construed to be limited to them, and suitable means for protection, oxidation, reduction and the like may be employed.
In the bi-cyclic-16-halogen compounds used in the present invention, enteropooling activity is remarkably enhanced when substituted by two halogen atoms, especially fluorine atoms, at the C-16 position independently of the structure and substituents of the five-membered ring or the existence of the double bonds or other substituents. Particularly preferable bi-cyclic-16-halogen compounds are those tautomers formed from mono-cyclic compounds having a ketone at the C-9 position and a hydroxyl group at the C-11 position in the five membered ring. Another preferable group is a bi-cyclic-16-halogen compound containing a 5,6-single bond, 5,6-double bond or those having the carbon number 20-22 where R1 contains 4 to 6 carbon atoms preferably in a straight chain.
An example of a mono-cyclic/bi-cyclic-16-halogen compound containing a 5,6-double bond are set forth below: 
Another embodiment of the present invention comprises the composition of the present invention and a medium chain fatty acid triglyceride. The triglyceride may be a saturated or unsaturated fatty acid having 6-14 carbon atoms that may have a branched chain. A preferred fatty acid is a straight chain saturated fatty acid, for example, caproic acid, caprylic acid, capric acid, lauric acid and myristic acid. 2 or more medium chain fatty acid triglycerides may be used as a mixture.
The composition of the present invention may be dissolved or admixed in the medium chain fatty acid triglyceride. The amount of the medium chain fatty acid triglyceride is not limited. However, generally, 1-1,000,000 parts by weight of the medium chain fatty acid triglyceride based on one part by weight of the bi-cyclic structure may be used. Preferably, 5-500,000 parts by weight, and more preferably 10-200,000 parts by weight.
Examples of the medium chain fatty acid triglyceride used in the present invention include a triglyceride of a saturated or unsaturated fatty acid having 6-14 carbon atoms which may have a branched chain. Preferred fatty acid is a straight chain saturated fatty acid for example caproic acid (C6), caprylic acid (C8), capric acid (C10), lauric acid (C12) and myristic acid (C14). In addition, 2 or more medium chain fatty acid triglycerides may be used.
Even more non-polar solvents, such as commercially available Miglyol can be employed to increase the bi-cyclic/mono-cyclic ratio.
To exemplify formulation of an embodiment of the present invention and to illustrate potential effect of steric hinderance, an Example is set forth.